Pneumatic tool.



PATENTED JULY 30, 1907.

H. R. PRINDLE & J. U. ADOLPH.

PNEUMATIC TOOL.

APPLICATION FILED IBB.26,1906.

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UNITED STATES PATENT QFFIGE,

HAROLD RITTENHOUSE PRINDLE AND JOHN ULRICH ADOLPH, OF PHILADELPHIA, PENNSYLVANIA.

PNEUMATIC TOOL.

Specification of Letters Patent.

Patented July 30, 1907.

Application filed February 26, 1906. $erial N0. 303,0'73.-

To all whom it may concern: 7

Be it known that we, I'IAROLD RITTENHOUSE PRIN- DLE and JOHN ULRICH AnoLPH, of Philadelphia, in the county of Philadelphia, and in the State of Pennsylvania, have invented a certain new and useful Improvement in Pneumatic Tools, and do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, in which Figure 1 is a longitudinal section of a pneumatic hammer embodying our invention; and, Fig. 2 is a top plan view with the handle removed.

The object of our invention is to control the movement of the valve of a pneumatic tool so as to prevent fluttering and breakage thereof, and to this end our invention consists in the pneumatic tool having the features of construction substantially as hereinafter specified and claimed.

The tool in which we have embodied our invention, and which has been selected by us for illustration is a pneumatic hammer of theconstruction shown in our United States Patent No. 724,736, April 7th, 1903, it comprising a cylinder A, a hammer B, and a grip-form handle G.

The valve D, as in the case of the valve of our patent, consists of a hollow cylinder having two circumferential or annular grooves d and radial openings or holes (2 placing the interior of the valve in communication with the respective circumferential grooves, but our present valveis unlike that of our patent in that its inner end is closed by a head or partition d the outer surface of Which closed end or head of the valve being a pressure-receiving surface for shifting the valve in one direction to reverse the stroke of the hammer, and the other end of the valve, which will be evident, has a ring or annular form, and of considerably less area than the closed end, being the other pressure, receiving surface for moving the valve in the other direction, and to such ring form or annular pressure-receiving surface of the valve live air is constantly admitted when the hammer is in operation, as in the case of the tool of our patent referred to, such air being passed from the air-inlet in the handle, and a portion of the air being permitted to escape to the atmosphere through small ports or passages 11 in the cylinder A for the reduction of the pressure on the valve. Notwithstanding the constant pressure of live air upon the ring-form or annular end of the valve, the valve is moved against such pressure when air is admitted to the inner or closed end of the valve, because'of the greater area of such closed end and the excess of pressure thereat. Air is admittedto act on the closed or headed end of the valve from the cylinder A through a port a, the inlet end of which port is uncovered when the piston or hammer completes its stroke when striking a blow.

As in the case of our patented tool, the valve is located in a valve box that consists of a shell E that surrounds the valve and a tube or hollow stem F which the valve encircles and which has at one end a flange f that fits an annular seat in one end of the shell E and a disk G between the valve, the shell and the tube and the end of the cylinder A. Thetube or stem F, as in the tool of our patent, is provided with two annular grooves F and radial holes F for cooperation with the annular grooves of the valve, and there are three annular grooves in the interior Wall of the shell E for cooperation with the valve for the supply of compressed air to the respective ends of the hammer and the exhaust of air, all as in the case of the tool of our patent, to which reference may be made for an understanding thereof, if necessary. Live air is supplied from the air inlet port in the handle through a port or passage f in the flange f of the tube or stem F to the valve box for action upon the annular or ring-form small end of the valve.

In the operation of tools having valves of the type we have illustrated, it has been found that the valve on completing its stroke strikes the wall orsurface at the end of its stroke, which is objectionable, first, because of the rebound which results in derangement of the proper, timely operation of the valve with reference to the stroke of the hammer, and second, because the constant blows of the valve by reason of its light structure, results in the breakage thereof, the blows causing crystallization of the steel and consequent shattering of the valve. To prevent this, we provide means for controlling the movement of the valve which, in the construction of tool illustrated in Fig. 1, consists simply of a closed chamber between the closed end or head of the valve and the adjacent end of the tube or stem F, which end is closed by a wall or partition f. With this arrangement, when the valve moves in one direction, the imprisoned air in the chamber thus formed is increasingly compressed as the stroke of the valve proceeds, and is sufficiently compressed before the stroke of the valve is completed to prevent the valve striking the end of the valve-box, while, on the reverse movement of the valve, the imprisoned air is expanded, and before the stroke of the valve in that direction is finished, has a sufficiently retarding effect upon the valve to pre vent the valve striking the wall of the valve box. To produce the retracting effect from the expansion of the air, it is, of course, necessary that the volume of the air be less than enough to fill the chamber at normal pressure, and, to assure this, a small portion of the air is permitted to escape during the compressing action of the valve, a minute perforation f 5 leading to the atmosphere being provided for this purpose.

Having thus described our invention, what We claim is:

1. In a pneumatic tool, the combination of a hammer, a cup-shaped valve, a valve box surrounding the valve, a stem which the valve encircles, said valve and stem providing a pressure chamber at one end of the valve actingon the valve to retard the travel thereof, a port leading to the atmosphere from said chamber and suitable ports controlled by the valve for the supply of pressure to the hammer.

2. In a pneumatic tool, the combination of a hammer, a cup-shaped valve having one end closed and the other open,

a valve box surrounding the valve, a hollow stem which the valve encircles, said valve and stem'providing a pressure chamber at one end of the valve acting on the valve to retard the travel thereof, a port leading to the, atmosphere from said chamber means for supplying fluid pressure on one side of the closed end of the valve to move it in one direction, and means for applying pressure to the valve to move it in the opposite direction.

In testimony that we claim the foregoing we have hereunto set our hands.

HAROLD RIT TENHOUSE PRINDLE. JOHN ULRICH ADOLPH.

Witnesses:

HARRY REDEKER, CARRIE REDEKER. 

